Does "Full Frame" Really Mean Much Anymore?
Camera sensors that that have the same size as a frame of 35mm film are known as "full frame." But most camera sensors are smaller than this — some quite a bit smaller. So does the term really mean much anymore? What is it we are all comparing against anyway?
If you think about it for a moment, every frame is a "full frame" in that it fills the frame left to right and top to bottom. Perhaps some frames are fuller than others. It would seem we need to dig into this further.
Back in the last century when everyone shot film, there wasn't any controversy about how big film was. Although there was 35mm film, and there were a variety of medium and large formats, people didn't really obsess over the difference. Well, except for some large format purists, but that's not what I'm talking about here. But once the age of digital photography began, nearly everyone began obsessing over the size and merits of competing camera sensors. It was felt that small sensors were inherently inferior, and nobody wanted to be associated with inferiority.
As the years have gone by though, sensor quality has improved across the board, and size isn't necessarily a prerequisite for quality anymore for most purposes. Sure, if you want the ultimate in quality for extremely large image reproduction, size matters. But for most of us, it's a bit more complicated than this.
You often hear people say that a full frame camera doesn't have a crop factor. The problem with this is that every camera crops the image. I'm sure you've noticed that lenses tend to be round yet images come in a variety of rectangular or square formats. Clearly things are getting cropped whether "full frame" camera owners want to admit it or not.
Indeed, the origins of "full frame" and "crop factor" are actually just the opposite of this. "Crop factor" came into use as a way of describing what percentage of "full frame" a given camera sensor actually measures, not the other way around. "Full frame" came first, thus necessitating the invention of "crop factor" as a way of describing sensors owned by people not lucky enough to own full frame.
Full frame sensors are not only bigger, they're more expensive than smaller formats. In order contain one, a full frame camera will generally be more expensive too. The obvious question is, if this is so, do you really need one?
Many of you reading this, and an even larger number who haven't discovered Earthbound Light yet carry a camera around in their pocket every day in the form of a smart phone. That would be hard to do if its sensor weren't so small. The entire camera, sensor and all, in a cell phone is generally no bigger than the fingernail on you little finger. No controversy about that not being full frame. But clearly it has advantages over full frame in terms of convenience. And for general use it can produce quite usable images.
While iPhone photography, or "iPhoneography," and the use of competing Android smart phones for photography have become quite trendy in some circles including some professionals, most us more "serious" photographers still stick to shooting with digital SLR cameras having sensor sizes at least closer to full frame. The most common DSLR sensor measures roughly two-thirds that of full frame, a format that has been come to be known as APS-C after the ill-fated similarly sized film format introduced by Kodak in the waning days of the film era. This is the size Nikon refers to as DX format. This size is commonly viewed as a compromise between the larger full frame format and the numerous tiny sensor formats used in smart phones and the like. Then there's also the fledgling Micro Four Thirds and Nikon 1 "CX" formats that lie in between Nikon DX APS-C and typical phone camera sensor sizes.
Looking at things from the vantage point of today, cameras and camera sensors come in all shapes and sizes. The so called "full frame" format just isn't the gold standard everyone shooting digitally aspires to anymore. It clearly has its place as do even larger medium format digital backs, but anything smaller doesn't have to automatically be looked down on anymore.
That's not to say that all things are equal of course. I've already mentioned that larger sensors can be capable of better quality for demanding needs. Bigger sensors can hold more and bigger pixels photosites capable of more accurately recording information. Sensor size also has an effect on depth of field for an equivalently cropped image since you need a longer focal length lens to achieve that crop than you would on a camera with a smaller sensor. The depth of field difference comes from the lens not the sensor of course, but with the inherent cropping difference due to sensor size it can seem to be a result of the sensor. The use of a large sensor can make extreme depth of field hard to achieve. The use of a small sensor can make it hard to avoid. Clearly there are differences.
I suppose in the end all of us need some terminology and standard of reference to compare and contrast sensor sizes if only to weigh the pros and cons of various formats. Unquestionably the term "full frame" has no real meaning anymore since few if any of us are shooting 35mm film anymore. Nonetheless we're stuck with the term. We have to call it something I guess. Either that or we'd need to designate some other sensor format as "standard frame" to measure everything against. At this point though, "full frame" has become a technical term for sensors measuring about 24mm x 36mm, but a term with little current relevance behind it.
So be it.